Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int main() {
  int H,W,count=0;
  cin >> H >> W;
  vector<vector<int>> V(H+2,vector<int>(W+2,-2));
  for(int i=1;i<=H;i++){
    string s;
    cin >> s;
    for(int j=1;j<=W;j++){
      if(s[j-1]=='.'){
        V[i][j] = -1;
        count++;
      }
    }
  }
  
  queue<pair<int,int>> Q;
  Q.push(make_pair(1,1));
  V[1][1] = 1;
  while(!Q.empty()){
    pair<int,int> u = Q.front();
    Q.pop();
    int x = u.first, y = u.second;
    if(V[x+1][y]==-1){
      V[x+1][y] = V[x][y]+1;
      Q.push(make_pair(x+1,y));
    }
    if(V[x][y+1]==-1){
      V[x][y+1] = V[x][y]+1;
      Q.push(make_pair(x,y+1));
    }
    if(V[x-1][y]==-1){
      V[x-1][y] = V[x][y]+1;
      Q.push(make_pair(x-1,y));
    }
    if(V[x][y-1]==-1){
      V[x][y-1] = V[x][y]+1;
      Q.push(make_pair(x,y-1));
    }
  }
  
  if(V[H][W]!=-1) cout << count-V[H][W] << endl;
  else cout << -1 << endl;
  return 0;
}